1. Field of the Invention
This invention relates to a process for activating catalysts which are commonly activated by reduction at elevated temperatures. In one embodiment, it relates to a process for activating nickel containing catalysts at temperatures lower than commonly employed for activation by a sequence of steps which includes the use of a reactive feed. In another embodiment, it relates to a method for activating massive nickel containing catalysts, particularly massive nickel-silica containing catalysts which also include copper and capable of having a reduced nickel surface area ranging from about 55 to about 100 m.sup.2 /g and a B.E.T. total surface area ranging from about 150 to about 300 m.sup.2 /g.
Many commercial hydrogenation units are limited to a maximum temperature at the inlet of about 200.degree. to about 250.degree. C. Since many reducing catalysts such as the nickel-silica catalysts must be reduced at temperatures of at least about 350.degree. C. for complete activation, it has been the practice to include a preheater furnace on commercial hydrogenation units to preheat the feed inlet to temperatures ranging from 350.degree. to 400.degree. C. The hydrogenation units which do not include preheaters require the use of the more expensive preactivated catalysts.
2. Description of the Prior Art
U.S. Pat. No. 3,173,388 to Schoofs described a process for recovering active catalytic material from an aluminum halide-hydrocarbon sludge. The aluminum halides (aluminum halide hydrocarbon complexes) described in the Schoofs patent are used in a Friedel-Crafts type process. The aluminum halide hydrocarbon complexes are gradually converted to a heavy aluminum halide-hydrocarbon sludge which decreases or eliminates the catalytic activity of the catalyst. Patentee teaches regeneration of this catalyst by treating the "sludge" with hydrogen at elevated temperatures and adding cracking hydrocarbons to the catalytic mixture to cause exothermic hydrocracking of the conjunct polymer.
U.S. Pat. No. 3,670,941 to Juhl et al discloses a process for the selective hydrogenation of olefinic unsaturated impurities present in aromatic hydrocarbon feed and subsequently regenerating the catalyst with hydrogen and a hydrocarbon liquid at elevated temperatures. Thereafter the regenerated catalyst is contacted with additional quantities of the aromatic hydrocarbon feed.
U.S. Pat. No. 3,696,026 to Conner et al discloses a method for activating a hydrocarbon cracking catalyst by reducing and sulfiding steps which preclude the necessity of removing water from the system.
British patent specification No. 1,158,418 discloses a process for reactivating Group VIII metal-containing catalysts by washing with an inert liquid hydrocarbon at a temperature below 200.degree. C., and then in a second step, washing with a stream of hydrogen at a temperature between 200.degree.-500.degree. C.
The prior art cited and described above does not pertain to the activation of reducing catalysts as provided by the process of the present invention. With the exception of the Conner et al patent, the above-cited patents pertains to either reactivation or regeneration processes. None of the above-cited patents pertain to the activation of reducing catalysts.
Massive nickel hydrogenation catalysts having a nickel surface area of more than 70 m.sup.2 /g are described in U.S. Pat. No. 3,697,445 to Carter. U.S. Pat. No. 3,868,332 teaches such a catalyst characterized as having a low sodium content, i.e., less than 0.2 wt. % based on total weight of catalyst. In U.S. Pat. No. 3,859,370 the use of this catalyst in hydrogenation processes is claimed.
U.S. application Ser. No. 577,328, filed May 14, 1975 in the names of James L. Carter and Allan E. Barnett discloses and claims a massive nickel catalyst wherein an improved activation is obtained by the incorporation of copper along with the nickel into the catalyst. The use of copper in the massive nickel catalyst enables one to activate the catalyst by reduction in hydrogen at lower temperatures. The temperatures disclosed and claimed include a range from 75.degree. to about 400.degree. C. An important difference between the catalyst activation procedure of the present invention and that of U.S. application Ser. No. 577,328 is that the present process requires two steps, one of which includes a reactive feed. By carrying out these sequential two steps within the limits defined and claimed herein a higher activity catalyst is obtained at lower temperatures.